Method of preparing a hydroxy functional vegetable oil

ABSTRACT

A simple, economical preparative method for the provision of hydroxyl functional materials that are derived by converting the alkene groups of the unsaturated molecules found in vegetable oils, into hydroxyl groups.

BACKGROUND OF THE INVENTION

The invention disclosed and claimed herein deals with a novel method of preparing hydroxy functional vegetable oils and the vegetable oils so prepared.

Vegetable oils have been familiar to man since prehistoric times and for centuries, humans have used fats and oils for food and a variety of other uses. Humankind has over the years perfected the science surrounding the ability to produce oils from agriculture products for their own use. Today, millions of pounds of such oils are used in a variety of end use applications.

Vegetable oils are made up principally of triglycerides containing both saturated and unsaturated moieties, wherein the predominant moiety is the unsaturated variety. Eventhough the triglycerides lend themselves to many end used applications, there are some needs for these materials to have functionalities different than those that are found in the raw vegetable oil.

For example, the triglycerides can be converted to hydroxy functional compounds and the hydroxy functional compounds can then be made useful, for example, in the formation of urethanes by reacting the hydroxys with isocyanates. Coatings, elastomers, foams and composites can be made from elastomers using such hydroxy functional compounds.

Currently, glycerides are hydrolyzed with water that is catalyzed by enzymes, acids, or metals to yield glycerol products, that is, where the ester groups are removed and replaced with carboxyl moities. Unsaturation in such molecules remains.

Fringuelli, and co-workers, have reported on a method to convert alkenes into 1,2-hydroxys using peroxy acids in deionized water. The process involves the epoxidation of the alkene, and then the epoxide ring is directly opened by organic acid and water, or via base hydrolysis to produce the hydroxy. It is stated by Fringuelli, et al that the synthesis does not require organic solvents. (Friguelli, F., Germani, R., Pizzo, F. and Savelli, G., ONE-POT TWO-STEPS SYNTHESIS OF 1,2 HYDROXY, Synthetic Communications, 19(11 & 12), 1939-1943 (1989).

What has been discovered herein is a simple, economical preparative method for the provision of hydroxyl functional polyols that are derived by converting the alkene groups of the unsaturated molecules that make up vegetable oils, into hydroxyl groups.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of the proposed reaction scheme to prepare the products of this invention and consists of parts 1, 2, and 3.

FIG. 2 is a graph of hydroxyl functionality versus the equivalents of peroxide used in the reaction to show the effect of excess peroxide.

THE INVENTION

The invention described and claimed herein deals with a method of preparing hydroxy functional vegetable oils. Thus, the invention comprises contacting a raw vegetable oil with hydrogen peroxide and an organic acid in the presence of water for a sufficient period of time and at a sufficient pressure, and at a sufficient temperature to form a hydroxy ester from unsaturated moieties in the vegetable oil, and thereafter separating any volatiles from the hydroxy functional vegetable oil, wherein the organic acid has from 1 to 20 carbon atoms.

What is meant by “raw” vegetable oil is vegetable oil that has been obtained by normal processing techniques, without any modification to the chemistry of the oil itself. This vegetable oil can be crude, refined, or modified, and can be used as obtained from the producers.

The vegetable oil is contacted with hydrogen peroxide and an organic acid in the presence of water. For purposes of this invention, the vegetable oil can be selected from any available vegetable oil, among which are the more common vegetable oils, such as corn oil, palm oil, soybean oil, cottonseed oil, peanut oil, rapeseed oil, safflower oil, canola, and sunflower oil. Preferred for this invention are corn oil, cottonseed oil, and soybean oil, canola oil and most preferred are soybean oil and palm oil.

In the method, the vegetable oil is contacted with hydrogen peroxide and an organic acid in the presence of water. The amount of hydrogen peroxide that is used ranges from about 0.1 to about 6.0 equivalents based on the amount of unsaturation that is in the vegetable oil. If a lesser amount of hydroxy functionality is desired, then smaller amounts of the peroxide should be used. As noted, about 6.0 equivalents will give a hydroxyl number of about 180. The effect of the use of larger amounts of the peroxide is illustrated in FIG. 2.

The amount of organic acid that is used is based on the amount of raw vegetable oil that is used, in that, there is used on the order of about 1:0.45 to about 1:2.0 molar ratios of grams of soybean oil to glacial acetic acid used, as the organic acid also acts as a solvent and is used in the ring opening reaction. For this invention, examples of organic acids that are useable are those having from 1 to 20 carbon atoms. Such acids are, for example, formic, acetic, propionic, n-butyric, isobutyric, 3-methylbutanoic, 2,2-dimethylpropanoic, n-valeric, n-caproic, n-heptoic, caprylic, n-nonylic, capric, undecylic, lauric, tridecylic, myristic, pentadecylic, palmitic, margaric, and stearic. Most preferred acids for this invention are formic and acetic because of the fact that they are essentially in liquid form at room temperature and are readily and economically available.

The water in the reaction comes from the peroxide that is used. At lower concentrations of hydrogen peroxide, more water is added to the system. As the molar equivalents of peroxide are increased, so does the amount of unsaturation converted to epoxide. The molar amount of peroxide used determines the molar amount of peracid formed. This, in turn, determines the amount of unsaturation converted to epoxide, then to hydroxyl compound.

The viscosity of the final hydroxylated vegetable oil ranges from 300 to 32,000 mPa·s and can be controlled either by the controlled oxidation of CSO, or by the length of the carbon chain on the acid that becomes the ester portion of the molecule in the product. Thus, wherein as R in RCOOH becomes larger, the viscosity decreases at no cost to functionality of the resultant polyol.

The inventor herein does not want to be held to such a theory, but the schematic reaction sequence illustrated in FIG. 1 demonstrates this point, wherein the designations R and R′ are the various segments forming the remainder of the vegetable oil. An organic acid, for example, acetic acid forms a peracid in the presence of peroxide, such as hydrogen peroxide, with formation of by-produced water, i.e. reaction scheme 1 (FIG. 1). Thereafter, the peracid reacts with the unsaturation in the vegetable oil to form the epoxide ring and a by-produced organic acid, as is shown in reaction scheme 2 (FIG. 1). Thereafter, the epoxide ring is opened by the influence of an organic acid to form the hydroxy ester as is shown in reaction scheme 3 (FIG. 1).

A variety of solvents may be used in this method. Any aprotic solvent may be used other than ethers, as they have been shown to form explosive peroxides.

The reaction time for this method ranges from about 1 hr. to about 24 hours.

The temperatures that are useful for the reactions can range from room temperature to the reflux temperature of the mixture.

It is preferred to add the peroxide and the organic acid to the vegetable oil at about the same time, but the order of addition can be changed.

The hydroxylated soybean oils of this invention are useful in the manufacture of a variety of polyurethane products. For example, they are useful in the preparation of a variety of reactive, curable polyurethane systems, such as reaction injection molding and castable elastomers. Such products can be for example, foams that are rigid, flexible, or semi-rigid. They can be high density and low density foams. Such foams, for example are useable for construction, such as insulation, and for the formation of articles, and for ornamental purposes.

In the examples, 35% hydrogen peroxide was used as the source of peroxide, so a very large excess of water is present. An excess of peroxide is used in order to convert all of the alkenes to epoxides.

EXAMPLES Example 1

Into a 500 ml. glass flask, there was added 20 gms. (19.52 mmoles) of solvent-free crude soybean oil. To the soybean oil at room temperature was added 40 ml. of glacial acetic acid and 10.71 ml of 35% hydrogen peroxide, for a ratio of peroxide to glacial acetic acid of 5:1.

This mixture was heated to reflux for about 1 hour, at which time the reaction mixture was clear. The reaction mixture was cooled down enough to handle the materials and the materials were placed in a glass separatory funnel and the bottom layer, (mostly acetic acid) was removed. The top layer was washed saturated sodium bisulfite, sodium bicarbonate (saturated solution) followed by saturated sodium chloride solution. The material was then transferred to an Erlenmeyer flask and dried over magnesium sulfate and then stripped of any solvent and volatiles by using a rotary evaporator.

An FTIR analysis showed a large OH stretch at approximately 3300 cm⁻¹ and a reduction in sp² CH stretch at approximately 3050 cm⁻¹ indicating that the unsaturation in the molecule had been converted to hydroxyl.

Example 2

A second run was made as in the first example, except there was used 4 equivalents of peroxide. There was used 20 gms. of crude soybean oil, 40 ml of glacial acetic acid, 6.7 ml of peroxide and the reaction was run at reflux for 1 hour. The FTIR analysis showed the formation of hydroxy compound, with a lesser reduction of sp² CH stretch at 3050 cm⁻¹ than showed in Example 1.

Example 3

A third run was made as in the first example, except there was used 3 equivalents of peroxide. There was used 20 gms. of crude soybean oil 40 ml. of glacial acetic, and 5.0 ml of peroxide. The reaction was run for 1 hour at reflux. The FTIR results were the same as Example 2,

Example 4

Four runs were made using (A)2 equivalents, (B)1 equivalent, (C) zero equivalent, and (D) 17 equivalents of peroxide. (A) consisted of 20 gms. of crude soybean oil, 40 ml. of glacial acetic acid, 3.3 ml of peroxide; (B) consisted of 20 gms. of crude soybean oil, 40 ml. of glacial acetic acid, 1.7 ml of peroxide; (C) consisted of 20 gms. of crude soybean oil, 40 ml. of glacial acetic acid, zero ml of peroxide, and 10 ml of water, and (D) consisted of 20 gms. of crude soybean oil, 40 ml of glacial acetic acid, and 11.7 ml of peroxide. All were heated at reflux for 1 hour.

Example 5

Another run was carried out in which two formulations were prepared. (A) consisted of 1 equivalent of peroxide (18.06 mmole), 0.25 equivalents of crude soybean oil, 36 ml. of glacial acetic acid, and (B) consisted of 10 equivalents of peroxide, 0.25 equivalents of crude soybean oil, 36 ml. of glacial acetic acid. After heating for 1 hour at reflux the material cleared. The analytical results showed that there was complete clarity of sample B with no apparent sp² CH stretch at 3005 cm⁻¹ for the unsaturated group. FTIR showed that when 1 equivalent of peroxide was used, the majority of the product was unsaturated with small amount of hydroxylated compound.

Example 6

Another run was carried out in which a combination to two acids was used. To a 1 liter round-bottomed glass flask was added 100 gms. of crude soybean oil, 17 ml of Glacial acetic acid and 35% hydrogen peroxide. To this mixture was added 11.1 ml of formic acid (a 1:1 ratio with the acetic acid). This mixture was allowed to heat at a low temperature (50° C.). The reaction mixture exothermed over the next 186 min. to about 105° C. The reaction was then maintained at 105° C. and allowed to stir for an additional 3 hours. After the reaction was complete, as was evidenced by the disappearance of the color of the reaction mixture, the acid was removed along with water to yield a quantitative conversion of alkene to epoxide, to hydroxy ester as shown by FTIR. 

1. A method of preparing a hydroxy functional vegetable oil, the process comprising contacting a raw vegetable oil with hydrogen peroxide and an organic acid in the presence of water for a sufficient period of time, a sufficient temperature, and a sufficient pressure to form alcohols from unsaturated moieties in the vegetable oil, and thereafter separating any volatiles from the hydroxylated functional vegetable oil, wherein the organic acid has from 1 to 20 carbon atoms selected from the group consisting of saturated moities and unsaturated moities.
 2. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein the vegetable oil is selected from the group consisting of corn oil, palm oil, soybean oil, cottonseed oil, peanut oil, rapeseed oil, safflower oil, canola, fish oils, beef tallow, lard, olive oil, and sunflower oil.
 3. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein the raw vegetable oil is contacted with a combination of the peroxide and organic acid essentially simultaneously.
 4. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein the raw vegetable oil is contacted with the organic acid first, and then contacted with the peroxide.
 5. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein the raw vegetable oil is contacted with the peroxide first and then is contacted with the organic acid.
 6. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein the time of reaction if from 1 to 24 hours.
 7. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein the temperature ranges from about 25° C. to about 125° C.
 8. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein the amount of organic acid that is used ranges from about 0.4 molar equivalents in volume to about 2.0 molar equivalents in volume based on the amount of raw vegetable oil.
 8. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein the organic acid that is used is a mixture of two or more organic acids.
 10. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein the amount of peroxide that is used ranges from about 0.7 to about 6.0 equivalents based on the amount of unsaturation in the raw vegetable oil.
 11. A hydroxy functional vegetable oil when prepared by the method of claim
 1. 12. A method of preparing a hydroxy functional vegetable oil as claimed in claim 1 wherein there is additionally present a solvent.
 13. A method of preparing hydroxy functional vegetable oil as claimed in claim 1 wherein the hydroxy functional vegetable oil that is obtained is extracted from the reaction mass using a solvent selected from the group consisting of toluene, methylene chloride, tetrahydrofuran, methanol, ethanol, and ethyl acetate.
 14. A method as claimed in claim 13 wherein following extraction, the solvent is removed and the hydroxy functional vegetable residue is subjected to distillation.
 15. A method as claimed in claim 13 wherein following extraction, the solvent is removed and the hydroxy functional vegetable residue is subjected to an evaporation step.
 16. In a polyurethane article, the incipient ingredients being a hydroxy functional vegetable oil of claim 11 and a urethane system reactive with the hydroxy functional vegetable oil.
 17. A method of preparing a cured polyurethane, the method comprising reacting a hydroxy functional vegetable oil as claimed in claim 11 with a reactive urethane system and allowing the polyurethane to cure.
 18. A polyurethane article prepared by the method of claim
 17. 19. A polyurethane article as claimed in claim 18 that is a foamed material.
 20. The foamed material as claimed in claim 19 that is a flexible foam.
 21. The foamed material as claimed in claim 19 that is a rigid foam.
 22. The foamed material as claimed in claim 19 that is a semi-rigid foam.
 23. The foamed material as claimed in claim 21 that is a construction foam.
 24. The foamed material as claimed in claim 23 that is used as insulation in construction.
 25. The foamed material as claimed in claim 23 that is an ornamental foam.
 26. A cured polyurethane article as claimed in claim 18 that is an elastomer material.
 27. A cured polyurethane article as claimed in claim 18 that is a castable material.
 28. A cured polyurethane article as claimed in claim 18 that is a carpet backing.
 29. The method as claimed in claim 17 that is a reaction injectable molding method.
 30. The method as claimed in claim 17 that is a castable molding method.
 31. The method as claimed in claim 17 that is a slab stock method.
 32. The method as claimed in claim 17 that is an extrusion method. 